1. Field of the Invention
This invention relates generally to hydraulic and pneumatic connectors and, more particularly, to connectors in which a coupling nut is fastened to a base element and is locked down so that it cannot back off due to vibration or other external forces.
2. Description of the Related Art
When a fluid-conducting tube is to be connected to an actuator, manifold, or similar hardware, a fitting is threaded into a base element or parent material of the hardware and the end of the tube is pressed over a projecting nozzle of the fitting. The projecting nozzle is axially aligned with the tube, and includes a fluid passageway extending completely through the fitting. Rotational movement of the fitting out of the base element is prevented by a lockring that is first pressed around a mid-portion of the fitting and, after the fitting is threaded into the base, is then pressed into a serrated counterbore in the base. Serrations on the fitting and the lockring prevent the fitting from rotating back out. A leak-proof connection of the tube and projecting nozzle is necessary and is provided by a B-nut, or coupling nut, that is threaded down over the tube end and onto the fitting past the nozzle to provide a seal. A lockwire is used to fix the coupling nut relative to the fitting so the coupling nut does not back off from the fitting due to external forces, such as vibration. The lockwire can be passed through holes formed in the coupling nut and secured to a boss on the base.
The use of a lockwire to fix the coupling nut relative to the fitting is cumbersome, and requires drilling a hole in one or more corners of the coupling nut and providing a boss or tie-down on the base. The lockwire is not a positive mechanical locking device, and installation of lockwires is subject to individual installation techniques, which can be inconsistent and unreliable. Furthermore, under some applications the use of lockwires to lock down the coupling nut is not permitted.
The co-pending parent application referred to above describes an improved hydraulic fitting lock that does away with a separate lockwire, and instead can use a sleeve that slides over the coupling nut between the nut and the base to engage both the coupling nut and the lockring. Axial movement of the sleeve can be prevented by inserting a clipwire through part of the sleeve and beneath the coupling nut so that the bottom of the coupling nut blocks movement of the sleeve. This arrangement, however, still makes use of a separate wire as the locking mechanism, which does not provide a completely consistent and reliable installation. Furthermore, the clipwire lock combination can still run afoul of some regulations that do not permit hydraulic fittings with a separate, removable locking mechanism.
From the foregoing discussion, it should be apparent that there is a need for an easy and reliable method and apparatus for positively locking the coupling nut or other connector of a fluid fitting to a base and providing a leak-free fluid connection without using a separate lockwire or clipwire. The present invention satisfies this need.